1. Field of the Invention
The present invention relates to a method for operating an output stage for at least one piezoactuator, a system for operating an output stage for at least one piezoactuator, a computer program and a computer program product.
2. Description of Related Art
In control units for so-called common-rail injection systems or CR piezo systems (DS) and direct gasoline injection systems or BDE Piezo Systems (GS), which include piezoactuators for acting on cylinders, based on systems-conditioned requirements of a cylinder selection (cylinder-select), at different times at the end of a charging or discharging process, switching off takes place. In BDE Piezo Systems, the cylinder-select is switched off exactly after the end of the charging and discharging time. This takes place independently of whether at that time there is still energy left in a transfer inductance of a piezo output stage. In CR Piezo Systems, after reaching the switch-off criterion, which is determined by the time during charging and the voltage during discharge, the cylinder-select is first switched off as soon as there is almost no energy left in the transfer inductance. For BDE-Piezo Systems it is usually provided for drive circuits that a charge is linearly applied to the piezoactuator. For this purpose, the cylinder-select is switched off immediately after reaching the switch-off criterion, such as the charging time, which is unfavorable, however, for maintaining the requirements with respect to electromagnetic compatibility (EMC) of an output stage of a control unit.
A method and a device for charging a capacitive element are known from published German patent application document DE 10 2007 014 326.